'I consider him to be a fat cat'

That's how Rick Perry described Mitt Romney in his interview with John Harwood, and that — maybe even more than his comments on President Barack Obama's birth certificate — is the siren-activating moment from their sit-down:

JOHN HARWOOD: And you mentioned class warfare. In 1996, when your advisor Steve Forbes was running on a flat tax, Mitt Romney said it was a tax cut for fat cats. If he says that about your plan, what are you going to say to him?

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RICK PERRY: Well I would said that he ought to go look in the mirror I guess. I consider him to be a fat cat. Because— here it doesn't matter to me what— what, you know, anybody says about this. I know what will work. And I'm more interested in getting people out there, investing in their companies— bringing back this— this money that's offshore.

Perry has taken shots before at Romney's wealth and background as a financier, but this is the most explicit and harsh one to date.